Physicians and dentists throughout the United States and indeed throughout the world utilize x-ray machines in the course of their medical practice. Such x-ray machines allow such practitioners to obtain pictures of their patient's bodies in order to help diagnose possible diseases, malformities, etc. In the case of dentistry, the dentist, orthodontist or oral surgeon can obtain pictures of a patient's head bones, such as their jaw bones, cheek bones, etc., as well as obtain pictures of a patient's teeth, in order to discover the location and orientation of impacted teeth, concealed cavities, jaw fractures, pathology, etc.
In the past it has been customary, when for example taking x-ray pictures of a patient's teeth, for the unexposed film to be inserted within the patient's mouth (intra-oral exposure) and for the x-ray machine collimator tube to be appropriately positioned so as to obtain an exposure of the desired teeth. Such procedures are many times uncomfortable for the patients because of the gagging reflex when the film is inserted deep within the mouth, and in addition, such procedures generally require many repositionings of the x-ray machine itself if multiple views of a patient's mouth and teeth are needed.
In the past it has also been customary to utilize much larger cross-section beams of x-rays when taking pictures of, for example, a patient's mouth than the size of the film to be exposed, whether or not the film is placed inside or outside the patient's mouth, and this is true even though collimator tubes has been employed to reduce generally the size of the beam to some extent. This is because in the past the possible harmful side effects of exposure to x-rays have not fully appreciated.
Recently it has become well recognized that exposure to x-rays is detrimental to human beings and has been associated with an increase in cancerous cell development. As a result, the United States Department of Health, Education and Welfare has recently issued rules requiring that x-ray beams, when used in medical diagnosis, be sufficiently collimated such that the beam size and shape exceed the size of the film by no more than two precent, regardless of the distance which may be required or desired between the x-ray machine and the film. Of course, the film utilized is also expected to be no larger than what would be reasonably necessary to obtain a picture of the area which is under medical investigation.
X-ray machines which include lead or lead-lined collimator tubes are expensive to make and replace, and thus to provide for the required collimation of an x-ray beam eminating from an x-ray machine already in medical use in a fairly inexpensive and easy fashion is desired.
According to U.S. Pat. No. 2,939,008 to Goodfriend, it has already been proposed to collimate an x-ray beam eminating from a lead-lined collimator tube of a dental x-ray machine by using a removable lead apertured diaphragm positioned at the end of the collimator tube adjacent the patient's head (the film to be exposed being outside the patient's mouth). In addition, it is noted therein that the usefulness of such a diaphragm is to reduce the size of the collimated x-ray beam in order to minimize the exposure of the patient to x-rays, while at the same time obtaining the desired radiograph of the patient's body, such as his head (e.g., temporomandibular joint). However, the mentioned "removable lead apertured diaphragm" is not described as to its specific structural features or its operation; thus, the Goodfriend disclosure is actually non-enabling in this regard in teaching those in the art how such a diaphragm would be constructed, how it might operate, how it might perhaps be removably attached to the collimator tube, etc.
Thus, it is an object of the present invention to provide a collimator cap which can be easily inserted over the output end of a collimator tube of an x-ray machine, e.g., a dental x-ray machine, in order to confine the beam of x-rays to a predetermined size and shape, and which can be easily removed and replaced.
Furthermore, it is an object of the present invention to provide a collimator cap which can be constructed of an inexpensive material, which need not necessarily be entirely impervious to x-rays, which can be fitted with replaceable diaphragms which are made of x-ray impervious materials such as lead, which have the appropriately sized and shaped apertures therein.
Furthermore, it is an object of the present invention to provide a collimator cap which is inexpensive to produce, which can be produced in varying sizes and shapes in order to fit the output ends of any collimator tubes on existing x-ray machines, and which can contain lead diaphragms in the form of apertured lead plates that are easily replaceable so that for any given distance between diaphragm and film and for any shape of film to be exposed, the x-ray beam will not be any larger than 2% of the dimensions of the film zone to be exposed.
In addition, it is an object of the present invention to provide an x-ray system, such as a dental x-ray system, which will employ the collimator cap of the present invention, and which will concurrently employ a film cassette and film cassette holder which will allow for four separate exposures to be made on the same film.
Further features of the present invention will be apparent in the arrangement and construction of the constituent parts in detail as set forth in the following specification taken together with the accompanying drawings.